Abstract

The microscopic optical quality of thick (∼1 μm) III‐V semiconductorepitaxial layers, mismatched to their substrates, is examined by photoluminescence microimaging. The layers include several kinds of strained‐layer superlattices (GaP/GaAsxP1−x, GaAs/GaAs1−xPx, and GaAs/InxGa1−xAs) and associated alloys. Microscopic images of epilayer luminescence directly reveal the presence of misfit dislocations which appear as dark line defects. These defects can be completely eliminated in the strained‐layer superlattices if these structures have thin layers, less than the critical thickness for elastic accommodation, and sufficient numbers of interfaces of block threading dislocations.